Process of electroplating metals



Patented Apr. 27, 1926.

UNITED STATES PATENT OFFICE.

ARNOLD MOHN, OF INDIANAPOLIS, INDIANA, ASSIGNOR, OI ONE-FOURTH TO JAMEI A. WALSH, OF INDIANAPOLIS, INDIANA.

PROCESS ELECTROPLATING' METALS.

No Drawing.

To all whom it may concern.

Be it known that I, ARNOLD MoHN, a citizen of Switzerland, residing at Indianapolis, in the county of Marion and State of Indiana, have invented certain new and useful Improvements in Processes f Electroplating Metals, of which the following 18 a specification.

My invention relates to the art of electroplating, which I accomplish in an extremely simple and efiicient manner without the employment of mechanical and electrical equip ment necessary in the methods of which I am aware; and by my process I am enabled to electroplate a variety of'metals and a lloys of permanent character and of SllifiOlent luster to obviate the necessity of extensively burnishing or otherwise especially finishing-the surface of the plated metal to insure the uniformity of deposit of the desired non-porous film and the polish thereof. The standard method of electroplating involves the use of an aqueous solution of the salt of the metal which is to be deposited, requiring tanks for the solution, spaced electrodes, and auxiliary sources of electric current. Another method is to immerse metal of a high electric solution tension into the salt of a less el'ectropositive metal whereby the immersed metal becomes coated with a film of the metal which is displaced from the salt solution. Such a deposit can not be very adherent for the reason that during this process the immersed metal has to dissolte or corrode. In another method of electroplating the metal articles, usually small pieces, which are to be coated, are agitated with a. dilute metal solution and zinc scrap, the zinc forming the anode, the metal solution the electrolyte, and the articles to be plated the cathode, in the process.

The methods referred to are'but briefly outlined in general, as they are well known to those skilled in the art, and are thus specified for comparative purposes in the description of my improvement in the art of electroplating, which is as follows:

I employ a metal of a relatively high electropositive character such positive metal being in preferably powdered or finely divided form. The metal or article to be plated as a rule is of a more negative character than the owdered metal and in addition to said pow ered metal I combine a pow- Application filed June 22, 1925. Serial No. 88,926.

ened instrumentality, such as a rag, waste or the like, when plating manually, or by an appropriate moisture creating buffer or other device, when plating mechanically. By either process I rub the mixture onto the metal to be plated, and the combination of materials and method of application, as stated, accomplishes the results explained. And it will be further understood that the presence of powdered or divided metal of a relatively high electropositive character is absolutely necessar in carrying out my invention, the Words relatively high electrop-ositive character referring to a comparison of the electrolytic solution tension of the metals involved in the process. The powdered or finely divided metal has a higher electric solution tension comparatively than the metallic or conducting article (as carbon) upon which the plating is to be deposited, or it has a higher electric solutron tension in comparison with the deposited metal or alloy. As an illustration of my improved process, I will describe a simple and practical example of theelectrodepo'sition of iron upon a copper plate. I moisten a rag and with itpick up powdered iron sulfate and powdered zinc, and rub this mixture upon the surface of a copper plate, with the is made upon the plate. This deposit of iron can be increased or built up by continuing the process described. By rubbin only moist iron sulfate, without powdered zinc, onto the copper plate, no deposit of iron results no matter how vigorously or how long the duration of this rubbing may be continued. Conversely, if I desire to deposit copper upon iron, I accomplish this by rubbing'moistened copper sulfate alone upon an iron plate, as is well known to those skilled in the art. But the resulting copper deposit, as is also well known, forms vbut a mere faint film upon the iron, which it is-impossible to increase or buildup by the further application of copper sulfate. Howresult that a smooth bright deposit of ironever, in carrying out my improved process, when I apply powdered zinc in fiddltlOndlO the powdered co per sulfate I can then build up the cop er eposit to any desired the ness. Un er no circumstances is it necessary to resort to outside electric current, yet the process of electrode osition carrled out according to my invention is accomplished in a smooth and practically even manner for the following reason. The selection of the powdered metal, of the metal salt, and of the metal to be lated, forms a combination of agencies which, under frictional contact in the manner disclosed, creates a galvanic cell. With this cell so formed the electric current brought about by the combined agencies, in the process of application as described, is flowing from the metal of a high solution tension to the metal of lower solution tension. The electric current is closed by the metals, powder and plate, the moment they are brought into frictional contact, and this current exists so long as the rubbing process continues, and which current so created accomplishes the electrolytic work in the manner disclosed.

In the deposition of iron upon copper, to which I have herein referred, the powdered zinc in effect functions and in acting as an anode, the iron sulfate is functionin as an electrolyte, and the copper late t rough which the current is complete in effect functions as the cathode, in the deposition of iron. When a certain amount or thickness of iron has been deposited in the manner stated, then this deposited iron itself takes the role of the cathode in my process, and the deposition of the iron continues, as I still have a current supplying cell in which the electric current flows from the zinc to the deposited iron. The method of building up the deposit of copper upon iron, as illustrated by the other example, is similar. It is therefore obvious from the examples given that I am not limited to the use of powdered zinc, as I have demonstrated in actual practice that powdered aluminum will function as satisfactorily in carrying out the process of electroplating, as it is only necessary that the combinations of metal powder, metal salt, and metal to be plated upon, create the proper current supplying galvanic cell.

For further illustration of my invention, I will illustrate the electroplating of barium upon a sheet of lead, which is accomplished in the following manner. I take powdered zinc and powdered barium chloride, and with a moistened rag I rub them, both together, upon a predetermined portion of the lead plate, with the result that the deposit is an alloy composed of barium and lead. This can only be attributed to the fact that the barium salt is applied in a highly concentrated form, that barium readily alloys with eeann lead, and that the allo thus formed has in this combination a ower electric solution tension than the metallic zinc, in other words, that an electric current flows from zinc to either lead or lead alloy.

It is also well known that some metals require higher degrees of heat to form a deposit, and by increased or varied friction I am enabled to var the degrees of heat necessary for depositing the metals requiring such treatment. The agency and the method of application explained are each very simple, and I have demonstrated in actual practice that itie possible to effectively deposit a large variety of metals by such process, some of which can be de osited only under the greatest difliculties y the present method of electroplating from dilute aqueous solution.

By my simple process of rubbing or friction and thus energizing the contacting elements it will be readily apparent that I may at all times have a suflicient amount of the selected metal to be discharged onto the metal which functions as the cathode, and that the quantity may be quite accurately determined; and this explanation is made for the reason that b methods now employed where it is requisite that only a part or parts of the cathode shall be plated it becomes necessary that those parts of the cathode requiring no plating must be protected or shielded by a stop-off preparation applied thereto, as paraffin and the like, so that the electrolyte employed shall not touch or decompose upon those portions of the cathode where no plating is required, while by some processes it is quite common to plate the entire cathode and then remove the undesired plated surface by grinding or otherwise, which methods, as will be apparent, involve waste of effort and material to pro duce the exact result desired. By my process, on the contrary, it is but necessary to directly apply the plating mixture to the precise portion of the surface of a metal functioning as a cathode as is desired without any surplusage of deposit and consequent removal thereof by grinding or otherwise, and, also, the necessity of especially arranged shields or stop-ofi preparations commonly used to confine the deposit to a restricted portion of the cathode is entirely obviated. It will be understood, however, that my simple process may be eifectively employed in connection with stencils and the like, as, for example, for purposes of lettering one metal upon another, as silver upon copper or brass, in which practice the stenciled cuttings are within certain boundaries within which the deposition by my process is confined, and such situation is not meant to be understood by the statement in the preceding sentence.

When using a plurality of salts of differmetal lea, or up r to form the plate or alloy.

ents metals in my process an almost unlimited number of alloys and metal mixtures can be deposited so lon as the articles to be plated upon, or the deposited metal or metals, are of such electric character that an electric current will be-created by the galvanic cell which is formed by combinations of the character herein illustrated, and which current flows to the metal to be plated upon.

While I have specifically set forth a sim-- ple manner in which I accomplish electroplating by my process it will be understood that under some conditions the plating or alloying of metals may require a wider range or more varied method of application than indicated, but in efiect such varied applications while apparently different would involve my principle though not practiced in the precise manner ex lained by me. For instance, should it be esired by my process to plate or alloy surface of a metallic tubular structure, then, as is apparent, a somewhat varying operation would no doubt he required to carry out the process,

in the tulce and rubbing of the powdered metal (or its equivalent in leaf form) and metal salt mixture accomplished by reciprocal action of the tool,- and some operations may require a hammering'or pressing action tormake the deposit of selected metal ditions the tool or instrument may bemade of metal, or may be of non-metallic character, and b simply wrapping thereabout a lying. powdered metal thereto in a suitab e manner,-in' either instance the combination-being such that a galvanic cell is formed which creates the current for the electrode osition. While I have specifie a metal in powlatter can also have the form of which ma be crumpled, or itmay be'a or bar, w ich is use in frictional contact with the metal salt and metal to be plated upon, which latter itself can be of varied form or she e. It may be a powder itself, and, after p ating with another metal in the disclosed new way, it canbe melted down to form an alloy in bulk form. All. such applications would in effect substantially involve my process, which, briefly, is the utilia' metal foil a metal with the interior that is to say, in plating such a structure a piston-like tool could be inserted ,metal to be p Under such con- -metal salts of the metals and frictionally the metal to be plated,

as the anode, this plate friction to a metal zation of powdered metal functioning as an anode, assimilating therewith a metal salt or mixture of metal salts functioning as an electrolyte, and applying such combination under friction or pressure to the article to be plated upon, thus forming the galvanic cell as hereinbefore described.

I claim as my invention:

1. The process 'of electroplating, which consists in employing a metal in powdere or divided form, mixing therewith a metal salt of the metal to be deposited, and ap lying said mixture under moisture and riction to the metal to be plated, said combination acting as a galvanic cell which creates the electric current for the decomposition 321d deposition of the metal contained in the s t.

2. The process of electroplating, which consists in employing a metal in owdered or divided form, mixing therewlth metal salts of the metals to be deposited, and appl ing said mixture under moisture and friction to the metal to be plated, said combination acting as a galvamc cell for the decomposition and de osition of the metals contained in said sa ts.

3. The process of electroplating, which consists in mixing powdered metal with metal salt of the metal to be deposited, and frictionally a plying such mixture to the ated said combination acting as a galvanic cell for the decomposition and de tosition of the'metal contained in said sa 4. The process consists in mixing powdered metal with to be decomposed, applying said mixture to said combination acting as a galvan c cell which creates the electric current for the decomposition and deposition of the metalscontamed in said salts. 5. The process of electroplating, which consists in mixing metal with a selected metal salt, and applying said mixture 'by or electric conductor, whereby a galvanic cell is formed for creating an electric current to decompose said selected metal salt and to deposit the metal contained therein upon said metal or electric conductor.

In testimony whereof I aflix my signature.

ARNOLD norm. 

